1. Field
The present disclosure relates to a sign display apparatus for a vehicle and a sign display method for a vehicle for displaying sign information on a traffic sign or a road marking on a display unit in a vehicle.
2. Description of the Related Art
A vehicle in recent years is equipped with an apparatus that displays sign information on a display unit in the vehicle. The sign information is detected from a traffic sign image captured by a vehicle-mounted camera. Road-to-vehicle communication is sometimes performed between a wireless transmitter (a beacon, etc.) set along a road and a vehicle-mounted wireless receiver. In the case where the sign information is transmitted from the wireless transmitter, the vehicle is also able to detect the sign information by receiving the signal of the sign information with the wireless receiver. Further, the vehicle is also able to detect the sign information from map information of an apparatus (a car navigation apparatus, etc.) that detects the position of the vehicle.
Apparatuses that display sign information on display units have been described in various literatures. For example, Japanese Unexamined Patent Application Publication No. 2009-110394 describes an apparatus that displays, when two or more signs are detected in sign information, the signs in the sign information in predetermined order on a display device in a vehicle (Claim 1 and paragraphs [0021] and [0043]). U.S. Patent Application Publication No. 2012/0046855 describes an apparatus that displays sign information on a display device and thereafter makes the sign information gradually disappear on the basis of any one of a traveling distance, an elapsed time, and vehicle speed (paragraph [0023] and FIG. 3).
The apparatus described in Japanese Unexamined Patent Application Publication No. 2009-110394 displays two or more kinds of sign information, for example, sign information of a maximum speed sign, and sign information of a school, kindergarten, nursery school ahead sign side by side on the display device (FIG. 6 of Japanese Unexamined Patent Application Publication No. 2009-110394). The apparatus of U.S. Patent Application Publication No. 2012/0046855 also displays two or more kinds of sign information, for example, two kinds of sign information of two speed signs side by side on the display device (FIG. 5 of U.S. Patent Application Publication No. 2012/0046855).
In place of the display devices described in Japanese Unexamined Patent Application Publication No. 2009-110394 and U.S. Patent Application Publication No. 2012/0046855, display devices may be used such as a display in a meter, a head-up display (HUD), and a display of a car navigation device. Usually, various kinds of information are displayed on these displays besides the sign information. Therefore, when information other than the sign information is preferentially displayed, it is difficult to display two or more kinds of sign information or complicated sign information (sign information containing textural information including many characters, etc.) in size recognizable for an occupant.